Anti-Ro/SS-a positivity and heat shock protein antibodies in patients with normal-pressure glaucoma

Purpose To describe the clinical and laboratory findings in 10 patients with normal-pressure glaucoma and anti-Ro/SS-A positivity by enzymelinked immunosorbent assay (ELISA) and to determine whether that positivity may be related to an autoimmune mechanism for the optic neuropathy. Methods In this prospective study, we evaluated ocular and systemic clinical findings of 10 patients with normal-pressure glaucoma and anti-Ro/SS-A positivity by ELISA, including sicca complex features. Ouchterlony immunodiffusion was performed to confirm the presence of antibodies for Ro/SS-A, and the presence of other serum antibodies and their possible cross-reactivities with Ro/SS-A were investigated. Results None of the 10 patients with normalpressure glaucoma and anti-Ro/SS-A positivity (by ELISA) had clinical or laboratory signs of Sjogren syndrome or other connective tissue diseases. Only one of 10 patients had evidence of anti-Ro/SS-A antibodies by Ouchterlony immunodiffusion. All patients demonstrated serum immunoreactivity to bacterial heat shock protein 60 (hsp60) by Western blotting. Cross-reactivity between bacterial hsp60 and Ro/SS-A was demonstrated by Western blotting. Immunoreactivity to bacterial hsp60 by ELISA was significantly elevated in the sera of patients with normal-pressure glaucoma. Furthermore, patients with either normal-pressure or primary open-angle glaucoma had increased serum immunoreactivity to human hsp60. Conclusions Anti-Ro/SS-A positivity by ELISA in 10 patients with normal-pressure glaucoma was associated with a high level of serum immunoreactivity to bacterial hsp60, which may indicate that their glaucomatous optic neuropathy involves an as yet unidentified autoimmune mechanism. The identification of autoantibodies that react with human hsp60 in patients with normalpressure and primary open-angle glaucoma may signify a common finding associated with the glaucomatous optic neuropathy process in some patients and appears to be unrelated to intraocular pressure levels.